Near-Ideal Xylene Selectivity in Adaptive Molecular Pillar[n]arene Crystals

Jie, Kecheng, Liu, Ming ORCID: 0000-0003-0008-1480, Zhou, Yujuan, Little, Marc, Pulido, Angeles, Chong, Sam ORCID: 0000-0002-3095-875X, Stephenson, Andrew, Hughes, Ashlea ORCID: 0000-0001-9625-6921, Sakakibara, Fumiyasu, Ogoshi, Tomoki
et al (show 4 more authors) (2018) Near-Ideal Xylene Selectivity in Adaptive Molecular Pillar[n]arene Crystals. Journal of the American Chemical Society, 140 (22). 6921 - 6930.

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The energy-efficient separation of alkylaromatic compounds is a major industrial sustainability challenge. The use of selectively porous extended frameworks, such as zeolites or metal–organic frameworks, is one solution to this problem. Here, we studied a flexible molecular material, perethylated pillar[n]arene crystals (n = 5, 6), which can be used to separate C8 alkylaromatic compounds. Pillar[6]arene is shown to separate para-xylene from its structural isomers, meta-xylene and ortho-xylene, with 90% specificity in the solid state. Selectivity is an intrinsic property of the pillar[6]arene host, with the flexible pillar[6]arene cavities adapting during adsorption thus enabling preferential adsorption of para-xylene in the solid state. The flexibility of pillar[6]arene as a solid sorbent is rationalized using molecular conformer searches and crystal structure prediction (CSP) combined with comprehensive characterization by X-ray diffraction and 13C solid state NMR spectroscopy. The CSP study, which takes into account the structural variability of pillar[6]arene, breaks new ground in its own right and showcases the feasibility of applying CSP methods to understand and ultimately to predict the behaviour of soft, adaptive molecular crystals.

Item Type: Article
Depositing User: Symplectic Admin
Date Deposited: 12 Jun 2018 10:48
Last Modified: 16 Sep 2022 03:12
DOI: 10.1021/jacs.8b02621